The purpose of this competing continuation application is to fund a training grant in the epidemiology of biodefense and emerging infections, continuing and expanding upon an existing training program in the epidemiology of emerging infections at the Harvard School of Public Health. The tragic events of September 11th, 2001, coupled with the deliberate exposure of the civilian population to Baccillus anthracis spores by means of the United States Postal Service, identified gaps in our nation's ability to identify and prevent a bioterrorist attack. Most recently, the epidemic of severe acute respiratory syndrome (SARS) in 2002-3 exemplified the potential for loss of life, major social disruption, and economic losses that can follow the introduction of a transmissible disease in a susceptible population. Although the SARS coronavirus was not deliberately introduced, it shared many of the characteristics of potential bioterrorist agents, and many of the contingency plans developed for dealing with biological attacks received their first tests in the SARS epidemic. As a result of these events, NIAID has prioritized research needed to link basic and applied research into the detection and prevention of emerging infectious diseases. The goal of the Harvard School of Public Health's Interdisciplinary Program in Infectious Disease Epidemiology (IPIDE) is to continue to train pre-doctoral students and add post-doctoral scientists to the program. Harvard's IPIDE combines training in epidemiologic methods, applied training in infectious diseases, and hands-on experience with infectious disease collaborations. Our trainees will benefit by collaborations with the Massachusetts Department of Public Health, the Brigham and Women's Hospital, and the Harvard Medical School. We propose to continue and expand our program by supporting 4 pre- and 2 postdoctoral students, allowing the next generation of investigators to address the complex and evolving issues arising in emerging infectious diseases and biodefense.